This invention pertains to aqueous compositions capable of removing grease and other oily substances from metal surfaces.
In preparing metal surfaces for the application of paint or other coatings, it will often be necessary to treat such surfaces to remove oily materials present as contaminants. For example, mill finish aluminum, such as the 6111 grade aluminum supplied by Alcoa for use by the automotive industry as car body panels, is difficult to clean using conventional alkaline cleaners and degreasers used in the industry in that such cleaners do not produce a water-wettable surface after cleaning. The non-wettable surface cannot be adequately pretreated with phosphate and the pretreated surface does not uniformly accept electrodeposition paint coverage. The resulting surface is rough and requires light sanding in order to obtain a color top coating of acceptable quality.
A composition useful for degreasing a metal surface is provided which comprises water, at least one surfactant, at least one alkalinizing agent, at least one metal corrosion inhibitor, at least one brightening agent, and at least one glycol ether. To obtain consistently high cleaning performance, it is critical to use a relatively high concentration of glycol ether (e.g., at least about 12 percent by weight, more preferably, at least about 15 percent by weight, most preferably at least about 18 percent by weight).